1. Field of the Invention
The present invention relates to structures, specifically flexible structures, used to separate and isolate bodies of water or other liquids, in ways to influence and maintain their qualities.
2. Prior Art
Open system fish cultures have used netting supported by buoyant material at their upper edges and anchored to the bottom. These open systems allow the surrounding waters to flow through the cultured species so that the condition of the open water is a determining factor in what happens within the culture. Location is paramount in such fish cultures and limits where they can function successfully.
Furthermore, these cultures pollute surrounding waters with their wastes and fish that escape and breed with wild fish affect the quality of the wild catch. These events have raised the concern of environmentalists and fishermen.
Recreational snorkeling and xe2x80x9cscubaxe2x80x9d diving are limited to warm weather and clean water, or during winter require expensive travel to, and accommodations in, warm climates with clean water.
To prevent waterborne pollutants from contaminating shorelines, a thick plastic matting was developed and a patent applied for by Gunderboom, Inc. The mattings are buoyed by floats at the upper edge and anchored by weights suspended from the bottom edge. It filters particles and oil based liquids (colloids) in suspension but allows dissolved inorganic and organic material to flow through with the surrounding waters. Thus, it cannot provide insulation against heat transfer, nor unpolluted or clear water. The Gunderboom must be fabricated in a single continuous piece to fit each site. Its matting rips under the repeated impact of wave action. Because it is made from one piece, it is difficult and costly to repair.
Complete isolation of waters have traditionally been accomplished by such civil engineering structures as earth and concrete dams and levees, concrete tank wall dividers and steel sheet piling, all of which resist horizontal forces rigidly. These conventional structures are expensive, take time to build and since they are inflexibly fixed, are difficult to remove. Furthermore, they may be hazardous to boats colliding against them.
Inventors later designed flexible buoyant underwater structures for storage or in which to work. U.S. Pat. No. 3,496,730 to Tsji (1970) discloses a gas filled undersea balloon which directed all forces into tensional stresses aligned with the plane of its surface. The balloon was to be of one piece, designed to resist forces at the particular depth where it would be anchored. U.S. Pat. No. 3,851,487 to Lambertsen (1974) discloses a one piece undersea balloon filled with a liquid whose specific density was lower than the surrounding water, so that it buoyed the balloon upwards from peripheral anchors. The inflated balloon formed a turbidity-free shelter for work underwater. But these structures, like the matted boom, are made from one piece, difficult and costly to repair. Besides the repair problem, each one piece balloon, with its tensional stress equal throughout the entire piece, would need a different thickness to provide enough strength for each depth at which it would be used.
U.S. Pat. No. 3,783,622 to Gambel is directed to a method and system for the containment and salvage of chemicals and oils at sea. This patent discloses a barrier system comprised of a plurality of rigid barrier units hingedly connected together to define an enclosure around a surface area of a body of water. Each barrier unit is provided with adjustable buoyancy and balasting chambers so that a nearly neutral buoyancy condition can be established with substantially all of the mass of the unit below the turbulence level of a body of water in which the barrier unit is placed.
Specifically, the invention is particularly suitable for isolating near shore bodies of seawater so that they can be filtered efficiently by keeping them from intermingling with the open sea, and heated efficiently by insulating between them and the open sea to reduce heat transfer. The simplicity of the invention and its resistance to tidal, current and wave forces make it practical and economical to operate a closed system for various objects, which include:
1. to provide a barrier against polluted or infested waters so that bathers may swim safely in the protected pure water.
2. to provide an environment for fish culture isolated from the conditions of the surrounding waters.
3. to provide a more suitable environment for work or exploration.
4. to provide a recreational area for diving and other activities in locations unsuitable for them because of climate and/or unsuitable water conditions.
5. to provide a means of isolating from surrounding liquid of differing quality, a body of liquid to accomplish any other purpose.
6. to provide a method of constructing the flexible structure easily, quickly and cheaply.
To accomplish these objectives, the invention has the following advantages:
1. Because it is composed of modules quickly assembled by unskilled labor, it cost much less than conventional structures designed to realize the same objectives.
2. Replacement of and repairs to modules of the structure are easier and cheaper to make than to a conventional monolithic structure.
3. The ease of disassembling the structure makes it easier to secure from government agencies, approvals for its installation and use in near shore bodies of water, than approvals for conventional permanent structures.
4. Because it is formed from an impermeable membrane that does not react with most liquids, it will not deteriorate is chemically due to long exposure in seawater, and so is more durable than conventional concrete and steel structures.
5. Buoyant top modules stretch the structure upward from anchors on the bottom, in tension, a stress easily resisted by a thin membrane.
6. The flexible structure changes form with tidal motion or flooding, so that it eliminates bending stresses. Thin membranes that resist only tension stresses are much cheaper than conventional rigid structures that resist bending stresses.
7. Where repeated reverse bending occurs, hinged joints prevent fatigue failure in the membrane.
8. Since the structure is composed of impermeable modules whose joints are sealed by flaps, liquid cannot pass through in large enough quantities to affect the liquid on the other side. This allows filters to effectively clean and treat the liquid. A conventional structure would require a lining of similar impermeable material.
9. The flexible structure also yields to waves, currents and impact loads, so it converts them into tensile stresses too.
10. The flexible structure is safe for boats and ships navigating around it and for fish enclosed within it, because it yields upon impact.
11. The membrane may insulate against heat transfer. A conventional structure would require an additional lining of similar insulation to reduce heat transfer. Combined with a prior art insulating mat on the surface of the enclosed water, this enables the water to be heated cheaply and efficiently by solar gain to a temperature comfortable for divers when the weather is frigid.
12. Reflective or colored surfaces create illusion of infinite distance in enclosures as if diving under an open sea.
13. Available diving trails in heavily populated areas where climate and water quality are otherwise unsuitable, form a viable and attractive way to dive without spending on travel, so that they will enlarge this increasing market to those less affluent, and extend its seasonal demand to a year round demand.
14. Cheaper quality control of larger bodies of water will incentivate large scale aquaculture by also lowering distribution costs to its nearby market.
Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description and operation.